Who invented this arched bridge?

“I saw a documentary where the army used made an arched bridge out of notched logs, like big Lincoln Logs. They were able to take it apart and move it when they were finished. Who invented it? Could you find more information about it?”

We were unable to find the documentary that our patron was referring to, but searching “Lincoln log military bridge” in an online search engine brought up images of a small-scale model matching our patron’s description. The image was from a blog called Dick 'n Debbie's Travels. It was a picture the writers had taken on their visit to a museum exhibit on DaVinci machines.

Now that we knew DaVinci was the inventor, and that the bridge was quite a bit older than we originally thought, it was easier to find more information. DaVinci designed a number of bridges, including several that could be easily built “so as to escape or follow the enemy” (according to Leslie Geddes’ translation of his notes in their essay). The bridge that looks like it’s made from Lincoln Logs is particularly special because it’s self-supporting and does not require rope or nails to hold it together.

The bridge was likely designed for Cesare Borgia (an Italian nobleman who inspired Machiavelli’s
The Prince) while DaVinci was employed by him in 1502 and 1503.

For more information, World of Invention, edited by Kimberly A. McGrath, and two books titled simply Leonardo DaVinci, one by Ludwig Goldscheider and one by Jack Wasserman, are available at the Newton Falls Public Library.